Police in Georgia investigating the death of a 22-month-old toddler have found disturbing Internet searches made on the father’s seized computers. A source told CNN that one Internet search included: “how long does it take for an animal to die in a hot car.”

Cooper Harris died on June 18 after his father, Justin Ross Harris, allegedly left him unattended in an SUV for seven hours in the sweltering heat. The father initially told police it was a tragic accident that happened after he forgot to drop his son off at daycare. But police grew suspicious.

“The chain of events that occurred in this case does not point toward simple negligence and evidence will be presented to support this allegation,” said Cobb County Police Chief John House.

Harris has been charged with murder and second-degree child cruelty. He’s pleaded not guilty to the charges.